MikeFellows
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| posted on 10/3/11 at 11:21 AM |
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Throttle Body Relocation
I have an 09 Busa engine and on the later engines the throttle bodies are a little higher than the < 08 engines, because of this I have very little
room to fit a airbox and the sausage filters give too much intake noise.
then I came across this
This is exactly what I want to do, but use a ram air intake into the plenum.
is this at all advisable (I dont know anything about throttle bodies or bike engines  )
Thanks
[Edited on 10/3/11 by MikeFellows]
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BenB
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| posted on 10/3/11 at 11:55 AM |
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If you look at the positive pressure created by ram air it's only worth it when going crazily fast. On a superbike it might be worth it but on a
7 based car I wouldn't bother (personally). A nicely sized plenum is just fine
Looking at that set-up though, if it's got trumpets inside the plenum the "top" of them will be awfully near the top wall of the
plenum which is a shame for flow.
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BenB
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| posted on 10/3/11 at 12:00 PM |
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http://www.zx11.info/zx11/uk3.htm
might be of interest- note only a few bhp extra up to 120mph
Ram air inlets are finely fettled things, do it wrong and you'll get extra drag and no extra power... Sevens have the aerodynamics of a brick
and tend to hit the aerodynamic quite early, you'll struggle to get up to the speeds needed to get significant ram air effect.
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Strontium Dog
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| posted on 10/3/11 at 12:24 PM |
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Hi Mike, first off I have never worked on a Busa engine but is the inlet angled up or is there a manifold that has angled pipes on it. It would likely
be better for flow to have straight inlet runners. This would also mean the bodies could be attached to the plenum more centrally than in the example
above. Also, try to radius as many of the corners and where the sides meet as possible as the angles formed will be bad for the air flow within the
plenum. Think of a cylinder with a soup ladle on each end over a square box if you get my drift! A saw a stainless steel thermos flask and a couple
of soup ladels actually used for this once on a smaller engine. Awesomely locost!
What you should be trying to achieve is an even distribution of the flow of air to each runner. On a normally aspirated engine bigger is usually
better (within reason) regards to the plenum and the inclusion of generous radii at entry to the runner usually has good gains for power. As above,
RAM air is unlikely to give you much if any gains but a decent cold air feed to the box will!
You can make a plenum out of lots of different materials too. GRP or carbon spring to mind as well as the more usual ally or steel. GRP makes it
comparatively easy to make a good functional shape that will fit in restrictive spaces.
Hope some of that is helpful
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MikeFellows
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| posted on 10/3/11 at 12:50 PM |
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Thanks for the reply's guys
the ram air soudns somewhat pointless now
I was more concerned about th e reposistioning of the throttle bodies on end of those 90 degree bends, are there any calcs for the length of those
runners, and is moving the TB's that far away from the head acceptable?
I will look into plenum design a little more before making it.
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JAG
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| posted on 10/3/11 at 01:18 PM |
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Moving the throttle bodies away from the head will improve mid range torque but at the expense of top end power.
Exactly how much I don't know but, as a general rule, longer inlets tend to lower the top end power while boosting mid range torque.
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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Strontium Dog
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| posted on 10/3/11 at 01:22 PM |
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You don't want those 90% bends if you can avoid them and you need to look at induction wave tuning to work out the right length of inlet runner.
There's loads of info on the web but heres a link or three to get you started
http://www.velocity-of-sound.com/velocity_of_sound/calculator1.htm
http://www.eng-tips.com/viewthread.cfm?qid=165529&page=1
http://www.rbracing-rsr.com/runnertorquecalc.html
[Edited on 10/3/11 by Strontium Dog]
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